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By Timothy R. Donahue, P.E.

Generally speaking, for a given structure, the higher the seismic response factor (R) value is, the more ductile the structure is and the lower the total seismic load acting on the building. With this concept in mind, one might conclude that reducing the seismic load acting on a building by selecting a more ductile seismic force restraint system (SFRS) with a higher R value would ultimately lower the material cost; however, when evaluating the overall cost implications for what it takes to achieve the increased ductility, the cost savings may not always be realized. This is primarily due to the requirements of overstrength factors in the design and detailing of the straps and other protected components of the SFRS with an R greater than 3.

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By John Worley, S.E. and Pierre Quenneville, Ph.D

“Residual drift” is the permanent lateral deformation of a building following an earthquake (Figure 1). In high seismic regions, buildings designed per code utilizing ductile seismic force resisting systems defined in ASCE 7 could experience excessive residual drifts in a major earthquake that may result in a damage level deemed to be uneconomical to retrofit and therefore be demolished.

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By Angela Joshi, EIT, Craig Barnes, PE, SE, Timothy Cella-Mowatt, PE, and Jibreel Mustafa EIT

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The 8-foot-deep University Club of Boston (UClub) trusses are vital parts of the building’s structure. They support the roof deck structure, roof-mounted mechanical equipment, and the weight of hanging items inside. But are they robust enough to support the proposed additional loads? The facility is undertaking a significant renovation from top to bottom.

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By Jerome F. Hajjar, Ph.D., P.E., NAE, F.SEI, F.ASCE

The construction and operation of the built environment accounts for a large portion of global greenhouse gas emissions. Governments, owners, occupants, architects, and engineers increasingly recognize the centrality of the structural engineering profession in our collective efforts to mitigate climate change. The United Nations (UN), through the Conference of Parties (COP) yearly intergovernmental summit aimed at creating global cooperation on issues of mitigating climate change, met in December 2023 in Dubai for COP28, at which they continued development of a Breakthrough Agenda.

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By Monica Schultes, PE

The Steel District office development in Sioux Falls, South Dakota, is the first to demonstrate the structural use of ultra-high-performance concrete (UHPC) in a commercial construction application in North America. Gage Brothers was instrumental in converting the design of a nine-story mixed-use building to a total–precast concrete structure. By using 69-foot-long UHPC beams, interior columns were eliminated, allowing open sightlines, more rentable space, and the ability for adaptive reuse in the future.

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By Matt Barnard

Somewhere, the earth is shaking. Earthquakes happen frequently throughout the world but often go unnoticed or are of little concern. Occasionally, earthquakes are much larger with shaking that impacts people and the built environment and cause tremendous loss of life, as we saw last year with the disaster in Turkey. In a world that seems to be more connected than ever, whether through our instantaneous sharing of everything to our global economies and supply chains, we now almost immediately see and then are impacted by these large earthquakes whether we have personally felt the shaking or not.

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By Joan Malana Kennedy

This is part 2 of a 2-part series about the developing issues in access to design data concerning digital collaborative working environments, particularly BIM. Part 1 discussed the background and BIM development in the UK, and the first reported formal dispute involving BIM in the UK, Trant Engineering Limited v Mott MacDonald Ltd [2017] EHWC 2061 (TCC). This article will deal with the lessons learned about TEL v MML [2017] and the implications and applications for designers.

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By Dr. Frank Griggs, Dist. M. ASCE

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Proposals to span the Mississippi River by a bridge were submitted by Charles Ellet, Jr. in 1840 for a 1,200-foot suspension bridge and by John A. Roebling in 1868 for another suspension Bridge. A local engineer by the name of Truman Homer proposed a tubular bridge similar to Stephenson’s Menai Straits Bridge in 1865 with three 500-foot spans. With the opening of several bridges upstream on the Mississippi, the City of St. Louis feared losing its claim as the gateway to the west and started to plan its own bridge. This would require a charter from both Missouri and Illinois as well as the federal government. On February 5, 1864, St. Louis received its charter from Missouri which stated in Section 6:

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Pleasanton, Calif. — Simpson Strong-Tie, the leader in engineered structural connectors and building solutions, has published its 2024-2025 Wood Construction Connectors catalog (C-C-2024), a comprehensive guide to the company’s most recent innovations, product line expansions and existing solutions for wood construction applications. The 372-page catalog offers extensive specification details and installation instructions for wood-to-wood, wood-to-masonry and wood-to-concrete structural connectors, as well as information on allowable loads, code reports, corrosion and coatings, fastener identification and more.

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STRUCTURE magazine